Question: Add.
Solution: There are many ways to solve this problem. Let's see two ways we can solve it. Place value table Let's line up the numbers by their decimal places. Tens Ones $.$ Tenths $3$ ${9}$ $.$ ${0}$ $4$ $6$ $.$ ${1}$ Because ${39}$ is a whole number, we can add a decimal point and a $0$ behind to make the columns align. Now, let's add each place value column. Tens Ones $.$ Tenths $\overset{1}{{3}}$ ${9}$ $.$ ${0}$ $+$ $4$ ${6}$ $.$ ${1}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $8$ $5$ $.$ $1$ Decomposing the numbers We can group the whole numbers together and the decimals together. $\begin{aligned} &({39} + {46}) + {0.1}\\\\ &=85 + {0.1}\\\\ &=85.1 \end{aligned}$ $85.1 = 39 + 46.1$